Bored pigs can start biting each other’s tails. It’s not hard to enrich their lives

To watch Adam Henson, my favourite farmer, on BBC’s Countryfile, giving a scratch to the belly of his favourite sow is sometimes to speculate about how we might have got on with pigs.

The notion occurred in the early days of our “self-reliant” experiments – bees, goats, poultry – when half the acre remained untamed and still full of juicy roots of thistles, briars and scutch. A pair of busy bonhams, judiciously controlled, might dig up the land, sift it of roots and dung it, all for free, with an eventual freezer full of pork.

This fantasy expired, perhaps wisely, but Henson’s regard for his friendly pigs can still make me wonder what pleasures we missed. His Gloucestershire old spots, a rare breed, are comfortably housed on straw, with fond husbandry and sorties to rummage in the sun – all of which can, of course, also seem somewhat fantastic compared with the real world of commercial pig farming.

In the research of Teagasc, the State agency that advises pig farmers among others, concern for productive welfare, both human and porcine, has long been high on the agenda.

In 1990 this column quoted from an article in the Teagasc journal Farm and Food Research by Dr Brendan Lynch, head of its pig-development team. Headlined “Are pig houses a danger to health?”, it quoted speculation that “in the worst conditions, pigs over gas-producing slurry might be teary-eyed, wet-nosed, nauseated, dizzy beasts in potentially explosive surroundings”.

The gases from slurry include ammonia, hydrogen sulphide, carbon dioxide and methane. Few years pass, wrote Dr Lynch, without some human deaths on Irish farms from hydrogen-sulphide poisoning. At high concentrations the gas even numbs the warning sense of smell. Methane, which is odourless, can (if rarely) explode.

My comments were properly appalled: “Does an intelligent, lively, affectionate animal have to be penned up between steel bars 168 hours a week, robbed of all natural exuberance and breathing poisoned air, to yield the profit margins of factory farming?”

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Nearly 30 years on, with constant advice and education from Teagasc, things have surely greatly improved. Personal, clip-on gas detectors, better ventilation, and more care in managing and pumping out slurry tanks have helped reduce the human risks. But while bedding on straw may indeed produce the happiest pigs, Ireland’s pig farms are still almost all fully slatted.

Supporting the animals on hose-washed grids above their accumulating slurry has several acknowledged risks to welfare, including lameness and bruising. But one that now gets prime research attention is that the pigs, bored out of their busy, inherently inquisitive, minds, may start biting each other’s tails.

Last year, in response to this seemingly common problem, the European Commissionissued a recommendation that materials introduced to divert the pigs from such habits “should be edible, chewable, investigable and manipulable and should sustain the interest of the pigs”.

I learn this from the current issue of Teagasc’s research journal, in which three scientists based at Moorepark, the organisation’s animal and grassland research and innovation centre, in Fermoy, explore “the use of different environmental enrichment options to prevent tail-biting in pigs” (online in its journal TResearch for autumn 2017).

The commonest diversion is to hang chains for the animals to chew on, or lumps of wood – but farmers worry about them swallowing splinters

All the pig producers they talked to spoke of the sporadic, unpredictable nature of the outbreaks, unrelated to the number or age of the pigs. The commonest attempt to divert the behaviour is to hang chains for the animals to chew on, or lumps of wood (but farmers worry about them swallowing splinters).

The Teagasc team carried out experiments, including the cost of providing the materials. They offered blocks of compressed straw in holders on walls and compared them with hanging plastic toys. The blocks were “prohibitively expensive”, at about €20,000 a year for every 500 sows, and did nothing to reduce the cortisol (the “stress hormone”) in the pigs’ saliva. Chewed hay can also clog pumping systems in the tank below.

The researchers also tried to find which kind of wood pigs prefer to chew and the cost of providing it. Of beech, larch and spruce, the animals most often consumed the softer, tastier but more expensive spruce (€2,286 a year for a herd of 500 sows).

For slatted piggeries, it considers the pros and cons of a whole range of “enrichments”, among them winding sisal or hemp rope round bars and hanging wood or hessian sacks. Only fresh root vegetables, such as turnips, beet and swede (not parsnips, toxic to pigs), are “optimal”, being “edible, chewable, investigable and manipulable”.

Ireland does, of course, have organic pig farmers of Adam Henson’s benevolent ilk, but they may be having some difficulty in bedding their animals on straw. A drop in Ireland’s cereal growing has apparently cut the supply by about a million bales.

This autumn, however, does offer organic pigs one enriching treat: a bumper crop of edible and interesting apples.

Michael Viney’s Reflections on Another Life, a selection of columns from the past four decades, is available from irishtimes.com/irishtimesbooks; viney@anu.ie